Constant speed drive for helicopter rotors



Feb. 7, 1950 c. P. HEINTZE i 2,496,624

CONSTANT SPEED DRIVE FOR HELICOPTER ROTORS Filed Aug. 27, 1945 I CARL PAUL HEINTZE /50 i INVENTOR I B zw AGENT Patented Feb. 7, 1950 UNITED STATES PATENT OFFICE 2.496.624 CONSTANT srEEn-p'nrvr: roitnrzucor'rnn noroas Cari an new", Amityville; N. r., minor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application August 2'], 1945, Serial No; 612,899

1 Claim. (Cl. 110-13522) This invention relates to means for obtaining constant velocity rotary motion in tiltable members, and more particularly to tilt mechanism for rotors for aircraft.

In aircraft of the type commonly known as helicopters, it is.desirable to have rotors that may be tilted with respect to the body thereof to obtain thrust at different angles for maneuvering and also for counteracting torque of one rotor by the tilt of another rotor. This invention employs constant velocity joint means for use in such rotor and the rotor itself and controls therefor are similar in some respect to that shown in the co-pending application of Igor I. Sikorsky, Serial. No. 698,947, filed September 24, 1946.

An object of this invention is to provide a tiltabie rotatable shaft with mounting means for obtaining a constant velocity in the shaft even when it is tilted with respect to a drive shaft therefor.

Another object is to provide an improved helicopter torque compensation rotor with constant speed tiltable means.

A further object is to provide an improved constant speed tiltable and rotatable shaft.

Other objects will be either obvious or pointed out in the following specification and claims and pertain to the details of construction and the arrangement of parts of the improved tiltable shaft means illustrated inthe drawing in a preferred embodiment, in which Fig. 1 is a plan view of a helicopter including my invention;

Fig. 2 is a view looking from the rear at the helicopter and including a vector diagram of forces exerted by the torque compensating rotor;

Fig. 3 is a view partially in section and partially in elevation looking from the side at the aft end portion of the helicopter;

Fig. 4 is a section taken along the lines 4-4 of Fig. 3 with parts in elevation;

Fig. 5 is a diagrammatic view of the total pitch control linkage to the torque compensating rotor; and I Fig. 6 is a diagram of the tilt linkage including a pair of universal joints and a slip joint jackshaft.

In Fig. 1, a helicopter I0 is provided with a main sustaining rotor having blades I! which turn in the direction indicated, and exert a torque tending to turn the body it of the helicopter in the opposite direction. A torque compensating rotor.- I! is arranged in a tilted plane with respect to the plane of rotation of the blades l2 .and exerts a lateral component of force opposing such torque. The rotor It also turns in a direction-opposite to the main rotor. In Fig. 2, the torque compensating rotor I4 is shown-as inclined upfwardly'and toward the right to exert a force in the direction indicated by the line ll of a vector diagram above the helicopter. The thrust line l8 will have a vertical component 20 which adds to the lift of the blades ii for sustaining the helicopter body l0, and a lateral component 22 for counteracting the torque of the main rotor. As more torque compensation is required, the torque compensating rotor I can be tilted more toward the right as viewed in Fig. 2 to exert a greater lateral component indicated by the broken line ,24 to offset the greater torque requirement. At this time, to maintain a constant lift as indicated by the vector 20, the thrust will have to be increased as represented by the thrust line26. This is accomplished by increasing the pitch of the blades. As less torque is required, the direction of the torque compensating rotor H can be more upwardly and the pitch of the blades thereof reduced to maintain substantially the same vertical component of lift 20. As more or less lift is required in the torque compensating rotor ll to control pitching of the body ill of the helicopter, the torque compensating rotor' I I can be rotated more nearly to the vertical pitch and th torque increased or reduced as the case requires to maintain substantially a constant lateral component of thrust indicated by the lines 22 and 24 to maintain a given heading for the helicopter.

As best shown in Figs. 3 and 4, the torque compensation rotor mechanism It is mounted within a tail cone 30 of the'body ID of the helicopter.

A gear housing 32 contains a bevel gear 34 turned by a shaft 36 from an engine, not shown. The bevel gear 34 turns a second bevel gear 38 to rotate a shaft 40 carried in bearings 42 in the housing 32. The shaft 40 turns one yoke of a universal joint 44 ofthe conventional type containing a central spider having pivots 46 and-.48 about which a jackshaft 50 containing a slip joint 82 can turn at an angle to the axis of the shaft 40. The iackshaft 80 turns a similar universal joint 84 which connects with a shaft 80 turning a head 88 that pivotaily mounts rotor blades of the torque compensating rotor I4. The shaft It is carried in a bearing 82 at its lower end adjacent the universal joint 54, and is suitably journaled at its upper end within a torque tube 84.

The torque tube 84 is mounted in a yoke 88 having legs 68 pivoted upon pins I0 in upstanding ears I2 on the housing 32. The pins I0 lie in a plane containing the axis of the shaft 40 and are located-midway between the centers of rotation of the universals 44 and'54 when the axis of the shaft 58 also lies in this plane. The torque tube 84 is tiltable by control'mechanism including an arm 80 formed as an extension of one leg 88 of the yoke 88 so that the torque tube 04 will rotate about the axis of the pins I0. The arm 80 is provided with a pivot 82 at its outermost end into which a link 84 pivots at its upper end. The link 84 is connected by a pivot 88 to one arm of a bell crank 88 mounted upon a pivot 00 is a pair of cars 02 formed at the sides of the housing 32. The other arm of the bell crank 88 is provided with a pivot 84 which rides in a slot 80 and connects with a screw 98 moved by a Jack I00 carried between ears I02 formed as lower extensions of the housing 32. The jack I00 is turned by a sheave I04 by cables I08 that are wrapped therearound and extend forwardly to the cockpit of the body I0, Fig.1, and are movable by foot pedals I08 by the pilot. When the cables lot are moved, the sheave I04 will rotate and turn the jack I00 to screw the shaft 98 in or out and rock the bell crank 88 and thus move the link 84 to rotate the arm 80 and tilt the torque tube 84. By such arrangement, the direction of thrust of torque compensating rotor mechanism I4 will be changed.

The total pitch of blades 50 is controlled by rocking the blades 60 around their longitudinal axes simultaneously through control mechanism IIO which comprises a collar II2 secured by ball bearings to a second collar II4 that is movable up and down by a rod H6 to thereby move the collar II2 up and down. Compression tension rods H8 will be moved with the collar H2 to rotate the blades 60 around their longitudinal axes to change their angles of incidence and thus change the power absorbed thereby and the total thrust of the torque compensating mechanism I4. The rod H8 is mounted in bearings I20 at its lower end within the torque tube 64. As best shown in Fig. 5, the rod H is provided with a clip I22 to which ends of cables I24 are attached. The cables I24 lead over pulleys I26 that are rotatably mounted within the yoke 88 and lead out to pulleys I28 through the pins which are hollow and mount the pivot pins of the pulleys I28. The cables I24 may connect with the cables I08 and be controlled simultaneously therewith under the influence of the pilot, or may be separately connected with the joy stick, not shown, or to other suitable control means in the cockpit. Such other control means are shown in the aforementioned co-pending application of Igor I. Sikorsky, Appl. Ser. No. 698,947.

It is readily apparent that the tilt of the rotor I4 and the pitch of the blades 80 may be varied to trim the helicopter with respect to its longitudinal axis to compensate for changes in the position of the center of gravity, C. G., in addition to counteracting the torque of the main rotor.

In Fig. 6, the arrangement of the universal 4 joints and the pivot for the torque tube 64 is illustrated. The universal 44 and the universal 84 are spaced from the axis through pivot pins 10 at distances represented by dimensions A and B. As the yoke 86 is rotated about the pivot pins 10 from the'position shown in solid lines to the position shown in broken lines, the dimensions A and B will be of exactly the same length, though the distanc between the universal joints 44 and 54 will vary for the entire movement. The slip joint 52 in the jackshaft 50 is provided so the jackshaft 50 may lengthen and shorten. The velocity of the shaft 40 will cause the jackshaft 50 when in an angled position with relation to the shaft 40. to have accelerations and decelerations of a magnitude determined by the angle I50 subtended between the axis of the shaft 40 and the axis of the jackshaft 50. Thus, for a constant velocity of shaft 40, the jackshaft 50 will accelerate and decelerate twice in each revolution. The angle I between the shaft 56 and the jackshaft 50 will be equal to the angle I50.

' Hence, the different angular velocity between the jackshaft 50 and the shaft 56 will be opposite and in the same proportion as the velocity differences between the jackshaft 50 and the shaft 40. However, because the cooperating pivots of the universals in the jackshaft lie in a common plane, so long as the angles I50 and I60 are equal to each other, the irregular velocity of the jackshaft 50 will not carry through to the shaft 56 but will be cancelled out. Thus, for a constant velocity in the shaft 40, the shaft 56 will rotate at the same velocity.

While I have shown and described on preferred embodiment and use for this invention, it will be clear that many other uses will occur to those skilled in the different arts. For example, it would be obvious to use a connection similar to this in conjunction with the universal couplings in other type vehicles than helicopters. It would also be obvious to use such constant velocity mechanism in conjunction with machines in which such function is desirable, and to ob-- tain a constant velocity in any direction by making the pivots I0 part of a universal joint having a center of rotation coincident with the point of intersection of the axes of the input and output shafts, or by use of other constant velocity universal joints. For these reasons, I wish not to be limited in my invention only to that particular form shown and described but by the spirit and the scope of the subjoined claim.

I claim:

In a helicopter, an elongated body, a main sustaining rotor rotatable about a generally upright axis at the fore part of said body, a tail cone pivoted about a fore and aft axis in said body having an auxiliary sustaining rotor mounted thereon, said auxiliary rotor when tilted by movement of said cone about said axis exerting a lateral thrust on said body, an upright power driven shaft in said body beneath said cone, a rotor shaft carried by said cone, and means for providing a constant speed relationship between said power driven shaft and said auxiliary rotor during tilting of said cone including a jack shaft located between said power driven shaft and said rotor shaft having telescoping extensible elements, a universal joint connecting one element of said jack shaft with said power driven shaft, and a second universal joint connecting the other element of said jack shaft with said rotor shaft, said universal joints being located equal distances from said fore and Number aft axis about which said cone pivots. 2,130,918 CARL PAUL HEINTZE. 2,135,073 2,139,963 REFERENCES CITED 5 2 273 303 The following references are of record in the 2385889 file of this patent:

UNITED STATES PATENTS Number Number Name Date 292,018 1,409,850 Haney Mar. 14, 1922 688,103 2,072,090 Anderson Mar. 2, 1937 Name Date DeStefano Sept. 20, 1938 Gerhardt et a1. Nov. 1, 1938 Leason Dec. 13, 1938 Waldron Feb. 17, 1942 Skavinsky Oct. 2, 1945 FOREIGN PATENTS Country Date Italy Dec. 31, 1931 France 1930 

